The present invention relates to a system and method for cooling an electric motor, and, more particularly, to a system and method for cooling the stator and stator windings of an electric motor for use in hybrid electric vehicles.
Electric motors, also referred to as E-machines, are commonly used in hybrid electric vehicles. Many of these motors include an interior rotor that rotates within an exterior stationary stator. The stator is often constructed of a plurality of stacked laminations (i.e., lamination stack) which support a plurality of stator windings.
These electric motors generate a considerable amount of heat during operation. If the heat is not adequately dissipated, the performance and reliability of the motors may be impaired. Early systems incorporated air cooling techniques to remove and dissipate the heat from the electric motor. Those air cooled arrangements were generally acceptable if the volume or size of the electric motor was large. However, the incorporation of E-machines in cars, trucks and other mobile vehicles makes their size and weight an important design concern. As the E-machines become smaller and more power dense, they become difficult to cool by air alone.
These design concerns led to the development of liquid cooling systems. However, these cooling systems have their own setbacks. Many of the known liquid cooling techniques utilize complex systems which require additional components to be installed in or around the electrical machine. Such designs result in additional manufacturing costs and processing time. More importantly, these complex systems also increase the overall weight of the E-machine. In the context of hybrid electric vehicles, an increase in weight often leads to a decrease in overall vehicular power and/or fuel efficiency.
Thus, there is a need for improvement in this field.